A cage of this type is described in DE 3706013 A1. The cage has two side rings which are connected to one another by webs. One of the side rings is arranged on one side of the cage above the pitch circle and another of the side rings is arranged below the pitch circle. The side rings of the cage are provided with annular grooves, starting from the end sides. Cages of this type are manufactured from plastic. Typical examples of materials which are used for the manufacture of cages of this type are polyamides which are reinforced with glass or with carbon fibers (for example, PA66/GF).
The side rings are also known as side rims. According to DE 3706013 A1, the annular grooves are provided in the side rims, in order to configure the wall thicknesses of the rims to be as thin as possible and in order to achieve uniform wall thicknesses in all regions of the side rims. Uniform wall thicknesses and wall thickness transitions are aimed for during injection molding of plastic parts, in order to avoid interruptions of the material flow/bubbles of the cage material in the cavities of the injection molding dies at the transition from thick to thin cross sections. Moreover, identical cooling speeds are achieved in all regions of the workpiece as a result of uniform wall thicknesses. Faults from undesired weakening in thin wall regions are also avoided by flow paths in cavities which are as short as possible with a relatively small injection cross section.
The thin-walled configuration is subject to limitations as a result of the requirements for high operating strength of the cage. Otherwise, thin-walled plastic parts are extremely unstable after removal from the die and frequently lose their intended shape or geometry during subsequent cooling and during storage.
Cages of the generic type under consideration are particularly difficult to design if they additionally have retaining lugs. Said retaining lugs are formed as a rule on one of the side rims and engage into a corresponding circumferential groove on one of the bearing rings of the inclined ball bearing. The cages, together with the balls and the corresponding bearing ring, are preassembled via the retaining lugs to form a structural unit, from which the balls which are snapped into the ball pockets of the cage cannot fall during assembly in the other bearing ring of the inclined ball bearing. Holding lugs of this type are also provided for axial path limitation of the cage in a bearing.
During assembly of the cage on the bearing ring, the retaining lugs are either compressed or extended elastically until the retaining lugs snap into a corresponding groove of the bearing ring. The wall thicknesses in the region of the transition of the retaining lugs into the cage and of the cage therefore have to be of sufficiently stable dimensions, in order not to be deformed plastically permanently during assembly of the cage on or in the bearing ring. On the other hand, the retaining lugs have to be elastic enough, in order not to make assembly of the cage in the bearing difficult and in order to prevent damage to the cage or the retaining lugs during assembly.